Jack Sock and Kevin Anderson saw off Roger Federer and Novak Djokovic 6-7 6-3 10-6 in the Laver Cup doubles to give Team World their first point of the tournament in Chicago.
Excitement had been building ever since it was announced the former world number ones would pair up for Team Europe in the competition's second year - with the blue side hoping to take a clean sweep into the weekend after a trio of singles wins earlier in the day.
Federer and Djokovic took a while to settle into the four-man format, the latter - on the back of his singles US Open triumph and 14th grand slam title - accidentally hitting his partner with the ball in the third game.
The Serbian and Swiss both laughed off the incident to the amusement of the crowd and went on to clinch the first-set tie-break 7-6 (7/5).
But their opponents soon found their rhythm, taking the second set 6-3, with Sock's experience as a three-time doubles major champion shining through on some impressive volley shots and Anderson displaying a strong serve.
The foursome went toe-to-toe in the early stages of the last set, but having seen their team-mates lose in two deciders earlier in the day, Sock and Anderson made sure not to waste their opportunity when Federer doubled-faulted at 4-4.
An impressive return winner from Sock sealed the set 10-6, giving captain John McEnroe a little relief before day two.
The doubles game followed three singles matches earlier in the day - Bulgarian Grigor Dimitrov putting the first point on the board for Europe after beating Frances Tiafoe 6-1 6-4.
Britain's Kyle Edmund, a Laver Cup debutant, claimed an impressive 6-4 5-7 10-6 win over Sock and match three saw Belgium's David Goffin add to Europe's advantage as he beat Argentina's Diego Schwartzman 6-4 4-6 11-9.
Schwartzman had looked to threaten Europe's lead with a second-set comeback, and dug deep at 5-1 down in the last to level at 7-7, but Goffin remained calm on his first match point to cheers and hugs from his team-mates and captain Bjorn Borg.
Team Europe now lead 3-1 with two points up for grabs on day two.
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